/// <summary>Checks against the guards for the command.</summary>
/// <param name="actionInput">The full input specified for executing the command.</param>
/// <returns>A string with the error message for the user upon guard failure, else null.</returns>
public override string Guards(ActionInput actionInput)
{
IController sender = actionInput.Controller;
string commonFailure = VerifyCommonGuards(actionInput, ActionGuards);
if (commonFailure != null)
{
return(commonFailure);
}
// Rule: A thing must be singly targeted.
// @@@ TODO: Try to find a single target according to the specified identifiers. If more than one thing
// meets the identifiers then use a disambiguation targeting system to try to narrow to one thing.
// @@@ TODO: This sort of find pattern may become common; maybe we need to simplify
// to having a Thing method which does this? IE "List<Thing> FindChildren<T>(string id)"?
Predicate <Thing> findPredicate = (Thing t) => t.Behaviors.FindFirst <EnterableExitableBehavior>() != null;
List <Thing> enterableThings = sender.Thing.Parent.FindAllChildren(findPredicate);
if (enterableThings.Count > 1)
{
return("There is more than one thing by that identity.");
}
else if (enterableThings.Count == 1)
{
Thing thing = enterableThings.First();
this.enterableBehavior = thing.Behaviors.FindFirst <EnterableExitableBehavior>();
if (this.enterableBehavior == null)
{
return("You can not enter " + thing.Name + ".");
}
}
// If we got this far, we couldn't find an appropriate enterable thing in the room.
return("You can't see anything like that to enter.");
}
